<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>Document</title>
</head>
<style>
  #circle-btn { 
    display: flex;
    align-items: center;
    justify-content: center;
    height: 100vh;
  }

  .btn-container {
    position: relative;  
  }

  button {
    border: 0;
    border-radius: 50px;
    color: white;
    background: #5f55af;
    padding: 15px 20px 16px 60px;
    text-transform: uppercase;
    background: linear-gradient(to right, #f72585 50%, #5f55af 50%);
    background-size: 200% 100%;
    background-position: right bottom;
    transition:all 2s ease;
  }

  svg {
    background: #f72585;
    padding: 8px;
    border-radius: 50%;
    position: absolute;
    left: 0;
    top: 0%;
  }

  button:hover {
    background-position: left bottom;
  }

</style>
<body>
  <div id="circle-btn">
    <div class="btn-container">
      <!-- // 这里有一个svg元素 -->
      <!-- <svg></svg> -->
      <button>Hover me</button>
    </div>
  </div>
</body>
</html>